Security screw



FIG. 1 is a front top perspective view of a security screw, showing our new design;

FIG. 2 is a front elevational view of thereof, with the rear elevational view, left side elevational view and right side elevational view being a mirror image of; and,

FIG. 3 is a top plan view of thereof.

The broken lines in the drawings illustrate portions of the security screw and form no part of the claimed design. 

CLAIM The ornamental design for a security screw, as shown and described. 